Out of Phase Chest Compression and Ventilation

ABSTRACT

A method for providing emergency care to a patient of an adverse cardiac event is disclosed that includes causing multiple chest compressions to be provided to the patient, and causing multiple inducements of ventilation to be provided to the patient. Particular ones of the multiple chest compressions can overlap time-wise with corresponding ones of the multiple inducements of ventilation, and can be substantially out of phase with the corresponding ones of the multiple inducements of ventilation.

CLAIM OF PRIORITY

This application claims priority under 35 USC §119(e) to U.S. PatentApplication Ser. No. 61/684,487, filed on Aug. 17, 2012, the entirecontents of which are hereby incorporated by reference.

TECHNICAL FIELD

This document relates to cardiac resuscitation, and in particular tosystems and techniques for assisting rescuers in performingcardio-pulmonary resuscitation (CPR).

BACKGROUND

CPR is a process by which one or more rescuers may provide chestcompressions and ventilation to a patient who has suffered an adversecardiac event—by popular terms, a heart attack. Chest compressions areconsidered to be the most important element of CPR during the first fiveto eight minutes after CPR efforts begin, because chest compressionshelp maintain circulation through the body and in the heart itself,which is the organ that can sustain the most damage from an adversecardiac event. Generally, American Heart Association CPR Guidelinesdefine protocols by which a rescuer is to apply the chest compressionsin coordination with ventilations. For example, current 2010 AHAGuidelines specify a ratio of 30:2 for compressions toventilations—i.e., thirty compressions for every two breaths. Andcompressions are to be performed at a rate of around 100 per minute.

CPR may be performed by a team of one or more rescuers, particularlywhen the rescuers are professionals such as emergency medicaltechnicians (EMTs) on an ambulance crew. One rescuer can provide thechest compressions and another can time their ventilations of thepatient to match the chest compressions according to the appropriate CPRprotocol. When professionals such as EMTs provide the care, ventilationis more likely to be provided via a ventilation bag that a rescuersqueezes, than by mouth-to-mouth.

The CPR can be performed in conjunction with providing shocks to thepatient from an external defibrillator, including from an automaticexternal defibrillator (AED) that is designed to be used by laypeople.Such AEDs often provide audible information to rescuers such as “pushharder” (when the rescuer is not performing chest compressionsforcefully enough), “stop CPR,” “stand back” (because a shock is aboutto be delivered), and the like. In determining how chest compressionsare being performed, certain defibrillators may obtain information fromone or more accelerometers (such as in the CPR D PADZ, CPR STAT PADZ,and ONE STEP pads (made by ZOLL MEDICAL of Chelmsford, Mass.) that canbe used to compute depths of chest compression, e.g., to determine thatthe compressions are too shallow to be effective and thus to cause thedefibrillator to speak the verbal cue “push header.”

Chest compressions and ventilation may also be provided mechanically.For example, the AUTOPULSE non-invasive cardiac support pump (made byZOLL MEDICAL of Chelmsford, Mass.) includes a back board and belt thatwraps around a patient's chest. A motor in the backboard causes the beltto cycle between tightening and loosening around the patient's chest soas to provide chest compressions automatically and periodically.Automatic ventilation has been provided to people with variousrespiratory problems by means of devices like a cuirass, in the form ofa shell that wraps around a patient's torso and applies negativepressure below their diaphragm, such as in the form of the HAYEK RTXrespirator from Medivent International Ltd. of London, UK.

SUMMARY

This document describes systems and techniques that may be used to helpdeliver coordinated CPR chest compressions and ventilation to a patientin need of emergency assistance. In typical application of chestcompressions, a significant amount of blood flows in a directionopposite to that desired. That is, during the compression downstroke,when blood should be flowing from the right side of the heart into thelungs for re-oxygenation, it is instead flowing in a retrograde fashionon the venous side from the thorax back into the abdomen. One factor forthis retrograde flow during the compression downstroke is the increasedvascular resistance of the lungs. But when abdominal compressions areproperly coordinated with chest compressions, the vascular resistance ofthe lungs can be overcome, and retrograde flow during the compressiondownstroke can be reduced.

The compressions occur according to a repeating cycle that repeatsaccording to the steps: act-hold-release-hold. For example, for chestcompressions, a rescuer or device may push downward on a patient tocompress the chest (act), may hold briefly at a bottom position, and maythen release and wait briefly (hold) before compressing again—in atypical and well-known chest compression cycle. To maximize theeffectiveness of the chest compressions, an abdominal compression maybegin slightly before the chest compression begins, such that thecompress-hold-release cycle for the abdominal compression is partiallycompleted before the chest compression begins. The properly-timedcompression on the abdomen will minimize the amount of blood flowingback into the abdomen during the compression down stroke. Thisparticular timing for what may be termed abdominal counter pulsationcauses abdominal compressions to be coordinated to coincide the earlydown stroke of chest compressions (rather than with the early relaxationphase) to reduce retrograde flow and enhance blood flow into the lungsfor reoxygenation.

The cycle generally has a constant periodicity, but the periodicity maybe changed as a rescue attempt continues. For example, venous congestionmay increase over time during a rescue operation, so that chestcompressions need to become more aggressive over time to push the bloodout of the heart and through the patient's body. As a result, theparameters of the chest and abdominal compressions may be varied,including the depth of compression, the periodicity of the cycles, thespeed of compression and release, the “dwell” period for anycompression, and the relative phasing of the two types of compressions.For example, while the chest compression may at first start when theabdominal compression is one-quarter complete, so that the chestcompression trails the abdominal compression by 90 degrees in phase, thephase difference may be caused to increase over time as the rescuecontinues so that compression on the abdomen is exerting lessbackpressure to the chest compression at the beginning of the phase ofthe chest compression.

Vascular resistance of the lungs may also be reduced by providingnegative pressure ventilation of the lungs during CPR. Current methodsfor ventilation during CPR are provided by various methods of positivepressure ventilation such as those delivered by what is termed abag-valve-mask combination with which a mask is placed over the victim'smouth and nose, and air is forced into the victim's lungs by squeezingthe ventilator bag. The bag may be replaced by various forms ofmechanically-powered ventilator devices. Unfortunately, any form ofpositive pressure ventilation increases the vascular resistance of thelungs, thus reducing forward blood flow from the right side of the heartinto the lungs for reoxygenation.

As described below, negative pressure ventilation may be provided toreduce lung vascular resistance. Negative pressure ventilation may beprovided by negative pressure on the abdomen rather than positivepressure. For example, a cuirass may be wrapped around the abdomen andmay pull outward on the abdomen, thereby pulling the patient's diaphragmdownward, and thereby causing the lungs to fill with air. Theventilations are delivered at a much slower rate than the compressions,for example one ventilation for every ten or so compressions. Negativepressure will be generated around the abdomen every tenth or socompression to cause air to enter the lungs. In some embodiments, thecuirass may also be capable of generating positive pressure to squeezethe abdomen synchronized to the compressions as described above. Thecuirass may also incorporate a mechanical compression element thatpresses the abdomen independent of the negative or positive pressurethat the cuirass generates.

In certain implementations, such systems and technique may provide oneor more advantages. For example, a patient may be provided with improvedcirculation of blood through the patient's lungs and the rest of thepatient's body. As a result, the patient's tissue main remain oxygenatedfor a longer period, and death of the tissue and of the patient may belessened or eliminated.

In one implementation, a method for providing emergency care to apatient of an adverse cardiac event is disclosed. The method comprisescausing multiple chest compressions to be provided to the patient, andcausing multiple inducements of ventilation to be provided to thepatient, wherein particular ones of the multiple chest compressions arecontrolled to overlap time-wise with corresponding ones of the multipleinducements of ventilation, and are substantially out of phase with thecorresponding ones of the multiple inducements of ventilation. In oneexample, the chest compressions and the inducements of ventilation areperformed at substantially constant rates that substantially match eachother. Also, each of the particular ones of the chest compressions canbegin while the corresponding ones of the inducements of ventilation areoccurring, or when the corresponding ones of the inducements ofventilation are about one-quarter complete. Similarly, each of theparticular ones of the chest compressions are performed approximately 90or 270 degrees out of phase with the corresponding ones of theinducements of ventilation.

In certain aspects, downward force on the patient's chest is applied foreach of the particular ones of the chest compressions while downwardforce is removed from the patient's abdomen during the correspondingones of the inducements of ventilation. Also, the multiple chestcompressions can be provided by an automatic chest compression unit andthe multiple inducements of ventilation are provided by an automaticmechanical ventilator. The chest compression unit can comprise a beltwrapped around the patient's chest or a piston pressing against thepatient's chest, and the automatic mechanical ventilator comprises acuirass. Moreover, the method can include automatically adaptivelyvarying parameters of the chest compressions, the inducements ofventilation, or both, in response to electronically monitoring acondition of the patient while the chest compressions are provided tothe patient. The automatically adaptively varying parameters of thechest compressions can also comprise changing a manner in which thechest compressions, inducements of ventilation, or both, are provided tothe patient, measuring a resulting change in one or morepatient-dependent parameters, and selecting new parameters for provisionof chest compression, inducements of ventilation, or both based on themeasured resulting change.

In another implementation, a system for providing coordinated chestcompressions and ventilation to a medical patient is disclosed. Thesystem comprises a substrate arranged to press against a patient, achest compressor attached to the substrate and positioned to providechest compressions to the patient, and a mechanical ventilator attachedto the substrate and positioned to engage the patient at the abdomen toinduce ventilations of the patient. The system can also include anelectronic controller programmed to actuate the chest compressor and themechanical ventilator so as to align chest compressions of the patientand ventilation of the patient in a predetermined manner. The electroniccontroller can be programmed to cause the chest compressions andventilation to be performed at substantially constant rates thatsubstantially match each other. Also, each of particular ones of thechest compressions can begin while corresponding ones of theventilations are already occurring, and the controller can be programmedso that each of the particular ones of the chest compressions begin whenthe corresponding ones of the ventilations are about one-quartercomplete, or that each of the particular ones of the chest compressionsare performed approximately 90 or 270 degrees out of phase with thecorresponding ones of the ventilations. Moreover, downward force on thepatient's chest can be applied for each of the particular ones of thechest compressions while downward force is removed from the patient'sabdomen during the corresponding ones of the ventilations.

In some aspects, the mechanical ventilator comprises a cuirass.Moreover, the chest compressor can comprise a belt positioned to wraparound the patient's chest and to be shortened in order to apply chestcompressions to the patient. The cuirass can be pneumatically powered,and can receive pneumatic power from a mechanism that is mechanicallycouple to a motor that drives the belt. Moreover, the electronicprogrammer can be programmed to automatically adaptively vary parametersof the chest compressions, the ventilations, or both, in response toelectronically monitoring a condition of the patient while the chestcompressions are provided to the patient.

Other features and advantages will be apparent from the description anddrawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is an overhead view of rescuers performing CPR on a patient usingan electronic system that instructs them in performance of the CPR.

FIGS. 2A and 2B show a side view of a patient being treated bymechanisms for performing coordinated chest compressions andabdominal-based ventilations.

FIG. 3 shows timing diagrams for the application of coordinated chestand abdominal compressions during CPR.

FIG. 4 is a flowchart of a process for performing coordinated CPR.

FIG. 5 is a chart showing blood flow at varying chest compressionrelease velocities.

FIG. 6 is a schematic block diagram that shows a defibrillator with anelectronic controller for providing automated CPR-related interaction.

FIG. 7 shows an example of a computer device that can be used toimplement the techniques described here.

DETAILED DESCRIPTION

This description discusses systems and techniques for guiding theprovision of care to a patient, such as the provision of CPR to apatient who has suffered cardiac arrest. For example, a portableelectronic defibrillator may be provided to rescuers and may includecommon features for delivering defibrillating energy (a shock) to apatient suffering from cardiac arrest through electrodes that may beplaced on the torso of the patient. The defibrillator may also beprovided with a mechanism for sensing the manner in which CPR chestcompressions are performed on the patient, such as a puck or similaritem that includes an accelerometer, and that may be placed under thehands of the person performing chest compressions and on top of thesternum of the patient. The defibrillator may use information from suchan item to identify the depth, rate, and timing of chest compressionsthat are being performed by a rescuer.

The system may further provide mechanisms for directing the user inperforming the compressions, and other mechanisms for directing anotheruser in compressing an abdominal area of the patient that is below thechest area, where the dividing line between the chest area and theabdominal area is defined by a location of the patient'sdiaphragm—though generally, it will be preferred to provide the forcesdiscussed here at a certain minimum distance above and below thediaphragm.

The mechanisms for directing the users in providing compressions mayinclude mechanisms for coordinating the chest compressions with theabdominal compressions, so that they occur in sequence and in apartially overlapping manner. In particular, for example, the system maydirect initiation of abdominal compressions slightly in advance ofdirecting initiation of chest compressions, so that the abdominalcompressions start first and are still occurring when the chestcompressions start. Thus, the chest compressions may be said to betrailing the abdominal compressions slight, such as by 90 degrees, or aquarter of a compress-hold-release sequence, or alternatively, a quarterof an entire compress-hold-release-hold cycle.

Compression of the abdomen may place positive pressure on the lungs, butnegative pressure may also be provided. For example, a cuirass mayprovide negative pressure to the abdomen, and thereby pull the diaphragmdownward and apply negative pressure to the outside of the lungs,thereby causing a patient to draw air in. Alternatively, a mechanicaldevice may be applied to the mouth of a patient to provide positivepressure to fill the lungs or negative pressure to empty the lungs, andthe provision of such pressure may be coordinated in an out-of-phasearrangement with chest compressions (e.g., with a phase differencesubstantially different than 0 degrees or 180 degrees), in the mannersdiscussed here.

The directions from the defibrillator to rescuers may occur in variousmanners, such as by audible prompts that are timed to when therespective rescuer should perform their compressions or other actions(e.g., squeezing a ventilation bag). For example, beeps of differenttones may represent an instruction for a respective rescuer to begin hisor her compression (where each rescuer is assigned a particular tone).To provide for the chest compressions to be trailing slightly, thepattern may be beep-beep-pause-beep-beep-pause—where the first beep ofeach cycle is aimed at the person performing abdominal compressions andthe second to the person performing chest compressions. Alternatively,the defibrillator may speak words such as “Belly—chest <pause>Belly—chest <pause>”, or similar directions that rescuers can easilyrecognize, remember, and follow, even in a high-stress situation.

FIG. 1 is an overhead view of rescuers 104, 106 performing CPR on apatient 102 using an electronic system that instructs them inperformance of the CPR. In this example, rescuers 104, 106 are alreadyin position and providing care to the patient 102, with rescuer 104 inposition and providing chest compressions to the torso of the patient102, and rescuer 106 providing ventilation by compressing the abdominalarea of the patient 102. The rescuers 104, 106 may be lay rescuers whowere in the vicinity of the patient 102 when the patient 102 firstrequired care, or may be trained medical personnel, such as emergencymedical technicians (EMTs). Although two rescuers are shown here forpurposes of explanation, additional rescuers may also care for thepatient 102, and may be included in a rotation of rescuers providingparticular components of care to the patient 102, where the componentsmay include chest compressions, ventilation, administration of drugs,and other provision of care.

In some examples, one or more therapeutic delivery devices (not shown)can automatically deliver the appropriate therapy to the patient. Thetherapeutic delivery devices can be, for example, a portable automaticchest compression device (e.g., with a belt that wraps around thepatient's chest) that may also include an abdominal compression orexpansion device, a drug infusion device, an automatic ventilator and/ora device that includes multiple therapies such as defibrillation, chestcompression, ventilation, and drug infusion. The therapeutic deliverydevices can be physically separate from the defibrillator 108, andcontrol of the therapeutic delivery devices may be accomplished by acommunications link from the defibrillator 108 that may be wired,wireless, or both.

In other examples, control and coordination for the overallresuscitation event and the delivery of the various therapies may beaccomplished by a device or processing element that is external to thedefibrillator 108, such as by use of a tablet-based computer that iscontrolled by one of the rescuers. For instance, such a device maydownload and process ECG data from the defibrillator 108; analyze theECG signals, perform relevant determinations like those discussed aboveand below based on the analysis, and control the other therapeuticdevices. In other examples, the defibrillator 108 may perform all theprocessing of the ECG, including analyzing the ECG signals, and maytransmit to a separate device only the final determination of theappropriate therapy, whereupon the separate device can perform thecontrol actions on the other linked devices.

An electrode assembly 110 is shown in position on the patient 102 in anormal position. The electrode assembly 110, in this example, is anassembly that combines an electrode positioned high on the right side ofthe patient's torso and an electrode positioned low on the left side ofthe patient's torso, along with a sensor package located over thepatient's sternum. The sensor package, which is obscured in the figureby the hands of rescuer 104 in this example, may include anaccelerometer or similar sensor package that may be used in cooperationwith a computer in the defibrillator 108 to generate an overall qualityscore for the chest compression, and the quality score may indicateinstantaneous quality or average quality across a time.

The score may indicate when and how the rescuer 104 is performing chestcompressions on the patient 102, based on signals from the sensorpackage. For example, as a simplified description, signals from anaccelerometer may be double integrated to identify a verticaldisplacement of the sensor package, and in turn of the sternum of thepatient 102, to identify how deep each chest compression is. The timebetween receiving such input from the sensor package may be used toidentify the pace at which chest compressions are being applied to thepatient 102.

The defibrillator 108 in this example is connected to the electrodepackage 110 and may operate in a familiar manner, e.g., to providedefibrillating shocks to the electrode package 110. As such, thedefibrillator may take a generally common form, and may be aprofessional style defibrillator, such as the R-SERIES, M-SERIES, orE-SERIES from ZOLL Medical Corporation of Chelmsford, Mass., or anautomated external defibrillator (AED), including the AED PLUS, or AEDPRO from ZOLL Medical Corporation. The defibrillator is shown in oneposition relative to the rescuers 104, 106 here, but may be placed inother locations to better present information to them, such as in theform of lights, displays, vibrators, or audible sound generators on achest-mounted component such as an electrode or via an addressableearpiece for each of the rescuers. Such feedback, as discussed morefully below, may be on units that are separate from the main housing ofthe defibrillator, and that may communication information about thepatient 102 and performance of CPR to the defibrillator 108 or mayreceive feedback information from the defibrillator 108, through eitherwired or wireless connects that are made directly with the defibrillator108 or indirectly through another device or devices.

Similar sensing devices may be used in conjunction with an item that maybe located under the hands of rescuer 106 who is compressing theabdomen. Such devices may be used to measure the depth and rate ofcompression by rescuer 106 in attempting to induce ventilations viamotion of the patient' abdominal region, and may employ accelerometersin a manner to that just discussed, in doing so. Such devices may bothhelp the rescuer position his or her hands properly, and also sensewhether the rescuer is performing the necessary actions properly so asto provide feedback to the rescuer as discussed above and below.

For illustrative purposes, two particular examples of feedback are shownhere on a display of the defibrillator 108. First, a power arrow 114provides feedback to the rescuer 104 regarding the depth of compressionthat the rescuer 104 is applying in each compression cycle to thepatient 102. In this example, power arrow 114 is pointing upward, andthus indicating to rescuer 104, that rescuer 104 needs to apply morevigorous input to create deeper chest compressions. Such feedback may beonly provided visually for performing chest compressions, in order tominimize the amount of information that the rescuer 104 must deal within a stressful situation. For example, an arrow indicating to apply lesscompression may not be shown under an assumption that very few rescuerswill apply too much compression, and thus the user need only respond toindications to apply more pressure. The particular type of feedback tobe provided can be determined by a designer of the defibrillator 108 andmay vary to match particular situations and implementations.

Separately, the rescuer 104 may be provided with additional limitedfeedback, such as feedback for performing chest compressions at anappropriate rate. As one example, the defibrillator 108 may emit a soundthrough speaker 118 in the form of a metronome to guide the rescuer 104in the proper rate of applying CPR. A visual representation may alsoindicate rates for performing compressions, such as a blinking of thedisplay on defibrillator 108. In addition, or as an alternative outputmechanism that is designed to avoid distracting rescuer 106, hapticfeedback may be provided to rescuer 104 through electrode assembly 110.

For example, a puck or other item on which the rescuer 104 places herhands may be provided with mechanisms for vibrating the puck similar tomechanisms provided for vibrating portable communication devices (e.g.,when an incoming telephone call is received on a smartphone). Suchvibrating may be provided so as to minimize the amount of informationthat can distract other rescuers in the area, and may also more directlybe used by the rescuer 104 to synchronize her chest compressionactivities with the output. For example, the vibrations may be periodic(approximate 100 times per minute) at the rate of performing chestcompressions when the rescuer 104 should be performing compressions andmay stop or be vibrated constantly when the rescuer 104 is to stop andswitch positions with another rescuer, such as rescuer 106. Withfeedback provided at the rescuer's hands, and because the rescuer 104 isproviding the chest compressions with her hands directly, input by thesystem into her hands may be more directly applied with respect to therescuer 104 keeping an appropriate pace. Such haptic feedback may alsorelieve the rescuer 104 of having to turn her head to view the displayon defibrillator 108. Thus, a first type of feedback, such as pulsedvisual, audible, or tactile feedback may be provided to guide a user inperforming CPR, and that type of feedback may be interrupted andreplaced with a different type of feedback such as constant sound orvibration to indicate that a rescuer is to stop performing theparticular component of CPR and let someone else take over.

Similar feedback may be provided to rescuer 106 in providing abdominalcompressions. For example, an image of a patient may be shown on thedefibrillator 108 display, and separate power arrows, like that justdiscussed, may be shown, respectively, over the patient's chest and overthe patient's abdomen. Each rescuer 104, 106 may then be able to seewhether they are providing the right effort and also acting at the righttime.

Feedback may also, or alternatively, be provided audibly, as discussedabove. For example, two different tones—one for the rescuer 104 and onefor the rescuer 106—may be generated at different sound frequencies andat the time at which the system wants to trigger the respective rescuer104, 106 to perform a compressive action. Also, the defibrillator mayspeak words, such as “belly” to trigger compression by rescuer 106, and“chest” to trigger compression by rescuer 104. The defibrillator maydetermine that one or the other of rescuers 104, 106 act more quickly ormore slowly than desired in response to the audible or visible prompts,and may change the timing of the prompts to adjust for such inaccuratereaction times by the one or more rescuers. For example, if abdominalcompressions are supposed to lead chest compressions by 90 degrees, andthe defibrillator 108 senses, via the mechanisms described above, thatthe lag is only 80 degrees (because the rescuer 104 has slower reactiontime than does rescuer 106), the system may move the audible promptsapart in time so that the delay between them is equivalent to 100degrees of a cycle, thus inducing the rescuers 104, 106 to be properly90 degrees apart in their real actions on the patient 102.

Cycling arrows 116 are shown separately on the display of thedefibrillator 108. Such arrows may indicate to the rescuer 104 and tothe rescuer 106 that it is time for them to switch tasks, such thatrescuer 104 begins providing abdominal compressions (which might bephysically easier)—as shown by the arrow superimposed over the legs ofrescuer 104 to indicate that she would slide upward toward the patient'sabdomen—and rescuer 106 begins providing chest compressions on electrodeassembly 110. Where there are three or more rescuers, the third rescuermay have been resting, and may take over chest compressions for rescuer104 when a rescuer change is directed by the system, and the rescuer 104may then rest or may provide abdominal compressions while rescuer 106rests or does something else. For example, the rescuers may readilydetermine that rescuer 106 does not have the strength to provideconsistent chest compressions on the patient 102, and may determine thatrescuer 106 should constantly provide abdominal compressions, whileother rescuers switch out in providing chest compressions. Thus, whenthe arrows 116 are displayed, rescuer 106 may stay in place while twoother rescuers switch places with respect to delivering chestcompressions. In the examples discussed here, the system may beprogrammed to be indifferent to the manner in which rescuers decide torotate, and the rotation may change during a rescue (e.g., rescuer 106may initially provide chest compressions as part of a 3-person rotationand may then bow out and just provide ventilation while the other 2rescuers rotate on chest compressions).

The defibrillator 108 may cause the cycling arrows 116 to be displayedbased on the occurrence of various events. In one example, the cyclingarrows 116 may be displayed after a set time period has elapsed sincerescuer 104 began applying chest compressions. For example, a particularCPR protocol may require switching of rescuers at certain predefinedperiodic intervals (e.g., every 2 minutes). As described below in moredetail, the cycling arrows 116 or a similar cycling signal, mayalternatively be generated according to determinations made by thedefibrillator 108 regarding the quality of chest compressions beingprovided to the patient 102 by rescuer 104, including by monitoring pastcompression parameters (e.g., rate over several compressions and depth)and monitoring the rescuer directly (e.g., by determining a pulse andblood oxygen level of a rescuer). Such an analysis may recognize thatrescuers tire progressively over time as they are providing chestcompressions, so that the depth of chest compressions is likely to fallover time, and the rate of chest compressions may also fall or becomemore erratic over time.

The defibrillator 108 may thus be programmed to identify when suchfactors indicate that the chest compression ability of the rescuer 104(and/or abdominal compression capability of the rescuer 106) has fallen,or is about to fall, below a level that is of adequate effectiveness. Asdiscussed below, for example, a score may be generated for the depth ofcompression based on how far from optimal compression each of therescuer's 104 compressions are. Another score may be generated based onhow far from optimal the rate of compressions are, and the two scores(depth and rate) may be combined to generate an overall quality scorefor each compression. A third score may indicate the rescuer's 104physical state (e.g., via pulse measurement) and that score may also becombined. A running quality score may then be computed to indicate thequality of compressions over a period of time, such as over the lastseveral compressions made by the user, so as to better indicate a trendin the quality of chest compressions being provided (in the past, thenear future, or both). When the quality score falls below a threshold,the defibrillator 108 may then generate an indication that the currentrescuer 104 should stop performing chest compressions and allow someoneelse to take over, such as by displaying cycling arrows 116.

Similarly, the quality of ventilation may be monitored. For example,providers of ventilation may tire. They may be reminded initially, suchas by a beeping metronome tied to the proper rate. As with reminders forchest compression, such a reminder may be provided constantly, whetherthe user is performing properly or not, or can be triggered to startwhen the user is initially identified as performing in a substandardfashion. Subsequently, if the substandard performance continues for apredetermined time period or deteriorates to a second threshold level;the performance trends in a manner that indicates the user is not likelyto improve the performance; or the performance otherwise indicates thatthe provider of ventilation should be switched out, a switchingindication may be generated. Also, whether for compression orventilation, different colors of lights may be used to indicatedifferent types of feedback, such as a green light for good work, ayellow light to indicate a temporary deviation from good work, and a redlight or even a blinking red light to indicate that the rescuer shouldswitch out with someone else.

Where the providers of chest compressions and of ventilation (e.g., viaabdominal compression and/or ventilation through a patient's mouth) areboth being monitored in such a manner, a signal to switch may begenerated when the first provider hits a substandard level.Alternatively, if chest compressions are considered more important thanis ventilation, the level at which ventilation will trigger a switch canbe set much more below a level considered to be satisfactory as comparedto a level for chest compressions. In other words, a system may bebiased to let the “weak” rescuer continue performing ventilation, ratherthan switching to a situation in which a somewhat fresh, but nonethelesstired with respect to squeezing a bag, and weak rescuer is placed in themost important position over another rescuer who may be more tired butis overall stronger at performing chest compressions. Various mechanismsmay be used to balance the multiple factors, which include the relativeimportant of each component to patient outcomes, the relative strengthof each rescuer, the current performance and trending of performance foreach rescuer, and knowledge or performance and trending for each rescuerfrom prior rescues (e.g., if the rescuers 104, 106 are part of an EMTteam that uses the same defibrillator multiple times, or who have theirdata from multiple rescues uploaded to a central system for analysis) orprior cycles in the same rescue.

The process of observing the quality of a component of the CPR, such asthe quality of chest compressions and providing prompts to the users inthe relative timing of their performance of chest compressions andabdominal compressions, may then continue recursively as long as care isbeing provided to the patient 102. For example, after the defibrillator108 generates an indication to switch providers of chest compression,the defibrillator 108 may sense through the electrode package 110 thatchest compressions stopped for a period, thus indicating that users haveswitched as suggested by the defibrillator 108. Once chest compressionsthen start again, the defibrillator 108 may again begin determining aquality score for chest compressions provided by the new rescuer, andmay indicate that rescuers should switch again when the qualityfalls—while all the time providing directions in the pacing of theprovision of both types of compressions. In certain instances, anindication to switch may be blocked from being generated for a certainperiod after a new user begins performing compressions, under theassumption that the user might not be tired, but is merely trying toestablish a rhythm in performing the chest compressions and abdominalcompressions. Also, trends in the quality of the particular CPRcomponent may be tracked rather than absolute values of the performance,so that the defibrillator 108 can distinguish situations in which arescuer is giving a poor chest compressions because he or she was tryingto find the appropriate rhythm or was distracted by a temporary problem,from situations in which the user truly is tiring and should bereplaced.

In certain instances, the defibrillator 108 may be adaptable todifferent CPR protocols. For example, the defibrillator 108 may beprogrammed according to a protocol that, among other parameters, callsfor each rescuer to provide chest compressions for a preset period oftime, or calls for a different alignment of phasing as between chestcompressions and abdominal compressions. In such a situation, thedefibrillator 108 may use pauses in the provision of chest compressionsto determine when users have switched providing chest compressions, andmay start a timer based on such observation. When the timer hits thepreset period, the defibrillator 108 may then provide an indication thatthe rescuer giving chest compressions is to change. The timer may thenbe reset once a next rescuer is identified as having started givingchest compressions, such as by recognizing a pause in the provision ofchest compressions.

Other protocols may be more flexible and may allow switches in rescuersto be dependent on the performance of the rescuers in addition to apredefined time interval, and to permit different phase differences tobe imposed as between chest compressions and abdominal compressions. Forexample, the defibrillator 108 may be programmed to indicate that chestcompressions are to trial abdominal compressions by 120 degrees oranother appropriate value. The defibrillator 108 may also be programmedto indicate that rescuers should change when it senses that performancehas fallen below an acceptable level, and may also indicate the need forchange when a maximum preset time has occurred even if the currentrescuer appears to be performed well. In such a protocol, the timeinterval may be substantially longer than an interval for a protocolthat requires changing based only upon elapsed time, and not upondegraded performance by the rescuer. Various different protocols maycall for changing of rescuers based on different levels in performance,or upon different elapsed time periods, or a combination of the two. Inparticular, AHA protocols are generally just guidelines, and aparticular medical director may alter such guidelines to fit theirparticular needs or professional judgment. (Indeed, revisions to AHAguidelines typically come from forward-thinking people who makemodifications to prior guidelines and find the modifications to beeffective.)

In such a situation, the defibrillator 108 may be programmed with theparameters for each of the protocols, and an operator of thedefibrillator 108 may select a protocol to be executed by thedefibrillator 108 (or the protocol may have been selected by a medicaldirector). Such a selection may occur at the time of a rescue, or at aprior time. For example, the ability to select of a protocol may belimited to someone who logs onto the defibrillator 108 or configurationsoftware separate from defibrillator 108 using administrator privileges,such as a person who runs an EMT service (e.g., a medical director ofappropriate training and certification to make such a determination).That person may select the protocol to be followed on each of themachines operated by the service, and other users may be prevented frommaking such changes. In this manner, the defibrillator 108 may be causedto match its performance to whatever protocol its users have beentrained to.

Thus, using the techniques described here, the defibrillator 108 may, inaddition to providing defibrillation shocks, ECG analysis, and otherfeatures traditionally provided by a defibrillator, also provideindications to coordinate provision of chest compressions with provisionof abdominal compressions, and to switch rescuers between variouscomponents of providing CPR and other care to a patient. Thedefibrillator may be deployed in the same manner as are existingdefibrillators, but may provide additional functionality in a mannerthat can be easily understood by trained and untrained rescuers.

Although the above description focuses on chest compression andabdominal compression, other rescuer activities may also be monitoredand prompted in a coordinated fashion. For example, a mechanicalventilation device may be provided at the patient's mouth to providepositive and/or negative ventilation to the patient in addition to, orinstead of, the use of abdominal compressions. The timing of suchventilation may be coordinated with the timing of the chest compressionsin an out-of-phase manner (e.g., out of phase by about 90 or 270degrees) so as to achieve the benefits of better lung circulation andless sloshing discussed above and below.

Each of the techniques discussed here for prompting manual chestcompression and abdominal compression may also be carried outautomatically in a device that mechanically provides chest compressionand abdominal compression or decompression, e.g., by a computercontroller in a medical device triggering mechanical devices such aselectric motors and/or pneumatic pumps or valves to actuate the motionof components that perform such actions on a patient. Examples of suchdevices are discussed next.

FIGS. 2A and 2B show a side view of a patient being treated bymechanisms for performing coordinated chest compressions andabdominal-based ventilations. In these examples, FIG. 2A shows a devicethat uses two belts 206, 212 to perform compression of the chest andabdomen in a coordinated manner, whereas FIG. 2B shows the use of a belt206 for chest compression and a cuirass for abdominal decompression. Thediscussions above and below about coordinated approaches applies equallyto each instances, unless clearly inappropriate, and generally with theopposite affect for decompression as opposed to compression.

Referring now more particularly to FIG. 2A, there is shown a medicaldevice 200 having a backboard 204 onto which may be placed a patient202, such as a person who is suffering from cardiac arrest (the arm ofthe patient has been truncated in the figure so as to better show thecomponents of the device 200). The backboard 204 has attached to it achest compression belt 206, which may be formed from two belt segmentsthat may open in front of the patient's 202 chest, wrapped over the topof the patient, and secured via hook-and-loop fasteners on each of thesegments that engages with hook-and-loop fasteners on the other segment.

The two segments of the belt 206 may be joined to an actuator in thebackboard 204, such as to a spindle that is connected to a stepper motorcontroller by a computer controller (not shown). The stepper motor maycause the spindle to rotate and the belt segments (which may be joinedin a single belt under the patient and at the spindle) to wrap aroundthe spindle and thus shorten in length around the chest of the patient202. In this manner, the device 200 may operate like an AUTOPULSE fromZOLL Medical Corp. of Chelmsford, Mass.

A second belt 212 may be positioned further down the backboard 204,closer to the patient's feet. This belt 212 may also include twosegments that are attached to a spindle in the backboard 204 forshortening and releasing the belt segments so as to induce compressionin the abdominal region. The spindle for belt 212 may be operated via asecond stepper motor or from the same motor as belt 206, where themechanisms for moving the spindles may be connected by a mechanicallinkage that may be able to provide an appropriate amount of phase delayfor coordinating the motion of the two belts in the manners discussedabove and below (e.g., in FIG. 3). Also, one or more of belts 206 and212 may be repositionable along the length of the backboard 204 so as toaccommodate patients of varying torso length. For example, the spindlefor belt 212 may be slidable along the length of the backboard 204 by upto several inches, and the belt 212, where it bends around the corner ofthe backboard 204, may pass around additional metal spindles that allowthe belt to slide easily as it is contracted and released. A rescuer maythen adjust the position of the belt 212 easily along the length of thebackboard 204 so as to match the relative dimensions of the particularpatient 202, who may be tall or short or in between.

In use then, the device 200 can be deployed from an ambulance and laidon the floor or ground next to a patient. Rescuer's may pull apart thebelt segments for belt 206 and belt 212, and lay them spread outwardfrom the backboard 204 on each side of the backboard 204. The rescuersmay then move the patient 202 into position on top of the backboard 204,laying on their back as shown in the figure. The rescuers may positionthe patient so that the belt 206 is positioned properly relative to thepatient's chest, and may close the belt segments in an overlappingmanner over the patient's chest so that the belt 206 is snug. The beltsegments may be held in this manner by the hook-and-loop fasteners thatcover opposed surfaces of the respective belt segments. The rescuers maythem slide the belt segments for belt 212 longitudinally along thebackboard 204 so that they are positioned below the patient's 202diaphragm and rib cage, and may secure the belt 212 in the same manneras the belt 206 was secures.

A rescuer may then activate the device 200, such as by turning on powerto the device—e.g., via a switch on device 200, or from a separatedevice, such as a defibrillator or computer (e.g., tablet computer) thatis used to control operation of the device 200. Such activation maycause the device to begin applying coordinated compressions to belts 206and 212, such as in manners discussed above and below. For example, belt212 may initially begin a compression, and belt 206 may begin itscompression a fraction of a second thereafter, before the belt 212 hasreleased from its compression, and possible while the belt 212 is stillincreasing its level of compression. Each belt may also include a dwellperiod and a release period when the tension on the belt segments isreleased, and those period may be the same for each of belt 206 and belt212, or can be different. The phase difference, the period of eachcycle, the rate of compression and decompression, the distance of thecompressions, and the time for each phase of a cycle may be set by amanufacturer, and in certain circumstances may be adjusted by a medicaldirector for a particular emergency service, or even in the field by therescuers.

FIG. 2B shows a similar device 200, but here the belt 212 has beenreplaced by a cuirass 208 and pneumatic tube 210 for driving the cuirass208. The backboard 204 and belt 206 interact as discussed above, andoperate as discussed above. The cuirass may include a plastic shieldthat lays across and seals to the patient's abdomen, and as such, wouldnot break at the midline of the patient's body, as did the belt 212.Rather, the cuirass 208 may be set entirely to one side of the backboard204 initially, and then swept over the patient's abdomen when they arein position, with straps on one side of the cuirass being initially freeof connection, but then connected on an opposite side of the backboard204. A rescuer may initially apply the cuirass at an appropriate levelof snugness around the patient, or the straps that hold the cuirass maybe attached to a motor that then snugs them up after the rescuer hascompleted the attachment.

The cuirass may then be operated in a well-known manner, but in thecoordinated manner described above and below. In particular, positiveand negative pressure may be created via pneumatic tube 210, wherepositive pressure will compress the abdomen, push the diaphragm upward,and push air out of the patient's lungs, and negative pressure will doeffectively the opposite.

In this manner, the mechanical device may result in optimized blood flowthrough a patient receiving CPR chest compressions through variousphases of the chest compressions. Blood flow into the lungs and thetorso may be increased by such coordination, and sloshing of the bloodwithout effective circulation may be reduced.

FIG. 3 shows timing diagrams for the application of coordinated chestand abdominal compressions during CPR. The diagram has three parts: onefor the timing of chest compressions 302, one for the timing ofabdominal compressions 304, and one for ventilation 306.

Referring more particularly to the graph for chest compressions 302, aline 308 shows the height of the patient's sternum relative to time. Thetimeline shows a little more than two complete compression and releasecycles, and if one assumes a rate of over 100 compressions per minutes,the total length of the 2 cycles is between 1 and 2 second. Thecompression line (moving from a high value to a low value) and thedecompression line both have a non-infinite slope, so as to indicatethat a rescuer or mechanical device cannot perform a compressionimmediately, due to resistance provided by the patient's body. Thehorizontal lower line segment indicates a brief dwell time in thecompression, though the flatness of the line is somewhat idealized.There is then a relatively long (though around ½ second) pause beforethe next compression occurs.

The graph of abdominal compression 310 is similar but leads the graph ofchest compression 308 slightly. In particular, the rates of the twographs effective match each other (e.g., over a period of multiplecompressions they, will be at the same average rate, and will vary formost individual particular compression cycles by less than 30%), and thedashed lines between them indicate that the abdominal compression leadsby about 90 degrees. Such phase different may be different in particularapplications, and will be a value that improves blood flow from thecoordinated compressions relative to uncoordinated compressions or tocompressions that are in phase or 180 degrees out of phase. Particularphase differences can be about 30 degrees to about 150 degree, ion apositive or negative direction between the two types of compressions(and depending on whether abdominal compression is being tracked orabdominal decompression).

The ventilation graph 306 shows the change in negative pressure in apatient's lungs during the compressions. The data here does not matchclassic ventilation rates (generally 6-10 breaths per minute), butinstead shows show the coordinated chest and abdominal compressions canaffect internal lung pressure.

FIG. 4 is a flowchart of a process for performing coordinated CPR. Ingeneral, the process involves applying coordinate chest and abdominalcompressions to a patient as part of CPR.

The process begins at box 402, where a patient in need of CPR isidentified. Such identification may occur, for example, by a civilianseeing another person undergoing what appears to be cardiac arrest(e.g., the person is lying pronate and unconscious). Such a civilian maythen take appropriate steps to determine that the person needs CPR andrelated life-saving measures. Alternatively, a rescuer such as an EMTmay be called by a dispatcher and may drive to the scene of someone whohas been reported as needing emergency attention, such as via athird-party calling a 911 service.

At box 404, a belt or, plunger or similar compression device is appliedto the chest of the person, not referenced as a patient (whether therescuer is a layperson or a healthcare professional) because they are inneed of medical assistance. For example, where the chest compressiondevice is in the form of a belt like that shown in FIGS. 2A and 2B, therescuer can place the patient on a backboard, and secure the belt snuglyaround the patient. The medical device may then further snug the belt toa predetermined degree, and may do so automatically upon being actuatedby a rescuer. Where the chest compression mechanism is a plunger, theplunger may be attached to a gantry that extends over the patient, orcan be on the inside of a belt that is wrapped around the patient.Again, the mechanism may be automatically positions against thepatient's chest in a manner that it is ready to begin giving accuratechest compressions to the patient.

At box 406, a belt, cuirass, or similar mechanism is positioned relativeto the patient's abdomen. Where the mechanism in a belt, like in FIG. 2Aabove, it may be wrapped around the patient and two portions of the beltmay be joined together above the patient's abdomen. The belt may then besnugged against the patent automatically upon the user activating thedevice to do so. Where the mechanism is a cuirass, the rescuer mayremove the patient's shirt and seal the shell of the cuirass against thepatient's abdomen, and may also tighten the shell to the patient, suchas using straps that attach to a backboard placed under the patient, asshown above for FIG. 2B. At this stage, the rescuer may check thepatient and the set-up of the device to confirm that each of themechanisms is properly positioned and ready to treat the patient. Therescuer may then activate the medical device to begin providingcoordinated compressions and/or decompressions to the patient's chestand abdomen. Thus, at box 408, coordinated compressions are applied tothe chest, and at box 410, coordinated motion is applied to the abdomen,where the coordination refers to coordination in timing of the motioninduced in the chest as compared to the motion induced in the abdomen.Such coordination may occur in the offset of the cycles as between thechest and abdomen, such as explained above and shown in FIG. 3.

At box 412, the phasing or other parameters of the chest and abdomencompressions are adaptively changed. For example, blood flow in thepatient at particular locations may be measured, and determinations maybe made whether the chest compressions are providing adequately bloodflow. If the blood flow falls from earlier in the process, changes canbe made to the relative phasing of the chest and abdomen compressions,the compress and release velocities for either may be changed, thedepths may be changed, or the dwell times can be changed. Such changesmay be made according to predetermined formulae or similar mechanisms,or in response to trial and error. In the former circumstance, it may beknown that chest compressions that go deeper must be provided later in arescue than earlier, and thus a medical device may be set toautomatically provide deeper compressions after operating for a time.For the latter circumstance, the relative phasing of the compressionsmay be changed in one direction by an amount, such as by 5 or 10degrees. The device may then measure the relative change in blood flowfrom such a change, and may maintain the changed phasing if the resultwas positive (e.g., better circulation), and return to the old phasingif the result was negative.

Simultaneous with providing the mechanical inputs discussed here, adevice or system may monitor the patient for a shockable rhythm, forpurposes of determining whether to deliver a defibrillating shock to thepatient. Such monitoring is common with portable defibrillators and maymake a determination that such a rhythm exists by using monitoringelectrodes that are part of a defibrillator electrodes system placedacross the patient's chest. If such a rhythm exists, a capacitor may becharged in the device, the rescuers may be notified and warned to moveback from the patient, and then instructed to press a button to causethe shock to be delivered. Each of the steps for performing theoperations on the patient may then be repeated until the patient iscapable of existing without the additional help.

FIG. 5 is a chart showing blood flow at varying chest compressionrelease velocities. The chart generally shows that blood flow increasesfor increasing release velocity, but that overall effectiveness of thecompressions may not increase because the increased flow occurs in theform of sloshing rather than effective circulatory flow. Such sloshingmay be lessened using the coordinated compression techniques discussedabove.

Referring more particularly to the chart, zone 502 shows multiplecompressions and release performed using a 200 msec release velocity,and the blood volume in liters per minute is 1 positive and 3 negative.The main relevance of such data is to show that there was significantsloshing (a period of peak forward flow followed by another period ofsignificant backward flow). Later, in zone 504, the release velocity wasdecreased so that the release required 300 msec. The volume fellslightly but not an appreciable amount. Later, in zone 506, the velocitywas increased to 100 msec, and the volume increase was significant, butdid so in both positive and negative direction—showing that in thisexample, increase velocity led to sloshing of blood in the test subject.And in zone 508, the administration of compressions returned to a 300msec rate, and the volumes were similar to those in zone 504 again.

That data shown here were obtained from a study of eight domestic swine(˜30 kg) using standard physiological monitoring. A flow probe wasplaced on the inferior vena cava. Ventricular fibrillation waselectrically induced. Mechanical chest compressions were provided by adevice that provided consistent sternal compressions. Chest compressionswere started after ten minutes of untreated ventricular fibrillation.The chest compression release time was adjusted so that sternal recoillasted 100 ms, 200 ms, or 300 ms. Chest compressions were delivered over54 min at a rate of 100 per minute and at a depth of 1.25 in.

The particular techniques described here may be assisted by the use of acomputer-implemented medical device, such as a defibrillator thatincludes computing capability. Similarly, the computing featuresdiscussed here may be included in a back board like that shown in FIGS.2A and 2B to control coordinated actuation of chest compression andabdominal movement devices in manners like those discussed above.

Referring now to FIG. 6, a schematic block diagram 600 shows an exampledefibrillator system 600, along with an example electrode package 602and compression puck 604. The defibrillator system is also provided witha back board 630 having a machine-actuated chest compression belt 626and machine-actuated abdomen compression belt 628. In general, thedefibrillator system 600 defines an apparatus or collection ofapparatuses for administering care to a patient who requires cardiacassistance.

Particular example components are shown in the defibrillator system 600to assist a rescuer with the provision of such care to a patient. Forexample, the defibrillator 600 includes a switch 606 and at least onecapacitor 608 for selectively supplying or applying a shock to asubject. The defibrillator 600 further includes an ECG analyzer module610, a trans-thoracic impedance module 612, a CPR feedback module 614that controls frequency and magnitude of chest compressions applied to asubject, a patient treatment module 616, a speaker 618, and a display620. In this example, the ECG analyzer module 610, trans-thoracicimpedance module 612, CPR feedback module 614, and patient treatment(PT) module 616 are grouped together as an electronic controller 623,which may be implemented by one or more computer processors. Forexample, respective elements of the electronic controller can beimplemented as: (i) a sequence of computer implemented instructionsexecuting on at least one computer processor of the defibrillator system600; and (ii) interconnected logic or hardware modules within thedefibrillator system, 600, as described in further detail below inconnection with FIG. 7.

In the example of FIG. 6, the electrode package 602 is connected to theswitch 606 via a port so that different packages may be connected atdifferent times. The electrode package 602 may also be connected throughthe port to ECG analyzer module 610, and trans-thoracic impedance module612. The compression puck 604 is connected, in this example, to the CPRfeedback module 614. In one embodiment, the ECG analyzer module 610 is acomponent that receives an ECG signal. Similarly, the trans-thoracicimpedance module 612 is a component that receives transthoracicimpedance signals that may be used in making determinations about when ashock can and should be delivered to a patient. Other embodiments arepossible.

Separately, a chest actuator 622 and abdomen actuator 624 may beprovided as part of the electronic controller 623. Though shown forillustration here as entirely in the electronic controller 623, inactual implementation, they may include relays or other actuatorstructures external to a processor, in addition to functionality formaking determinations for actuating such structures. For example, asdiscussed above, the electronic controller may be programmed toimplement automatic contraction and release of belts 626 and 628 in anoff-phase relationship so as to improve circulation provided by chestcompressions. Also, such actuating structures may be provided in adevice that is physically separate from a defibrillator, such as in theback board 630, which may communicate wirelessly with the defibrillator.In addition, the timing determinations made by the chest actuator 622and abdomen actuator 624 may be output in other ways, such as via pacingsounds delivered to speaker 618 and feedback information delivered todisplay 620, in manners like those discussed above. In certainimplementations in which the chest belt 626 is provided, the puck 604may be unnecessary.

The patient treatment module 616 is configured to receive an input fromeach one of the ECG analyzer module 610, trans-thoracic impedance module612, and CPR feedback module 614. In addition, the patient treatmentmodule may also receive input about the positions of belts 626 and 628,or the state of actuation of the belts 626, 628. The patient treatmentmodule 616 uses inputs as received from at least the ECG analyzer module610 and trans-thoracic impedance module 612 to predict whether adefibrillation event will likely terminate an arrhythmic episode. Inthis manner, the patient treatment module 616 uses information derivedfrom both an ECG signal and transthoracic impedance measurement toprovide a determination of a likelihood of success for delivering adefibrillating shock to a subject.

The patient treatment module 616 is further configured to provide aninput to each one of the speaker 618, display 620, and switch 606. Ingeneral, input provided to the speaker 618 and display 620 correspondsto either a success indication or a failure indication regarding thelikelihood of success for delivering a shock to the subject. In oneembodiment, the difference between a success indication and a failureindication is binary and based on a threshold. For example, a successindication may be relayed to the display 620 when the chancescorresponding to a successful defibrillation event is greater than 75%.In this example, the value “75%” may be rendered on the display 616indicating a positive likelihood of success. When a positive likelihoodof success is indicated, the PT module 616 enables the switch 606 suchthat a shock may be delivered to a subject. In another embodiment,likelihood of a successful defibrillation event may be classified intoone of many possible groups such as, for example, low, medium, and highlikelihood of success. With a “low” likelihood of success (e.g.,corresponding to a successful defibrillation event is less than 50%),the PT module 616 disables the switch 606 such that a shock cannot bedelivered to a subject. With a “medium” likelihood of success (e.g.,corresponding to a successful defibrillation event is greater than 50%but less than 75%), the patient treatment module 616 enables the switch606 such that a shock may be delivered to a subject, but also renders awarning on the display 620 that the likelihood of success isquestionable. With a “high” likelihood of success (e.g., correspondingto a successful defibrillation event is greater than or equal to 75%),the patient treatment module 616 enables the switch 606 such that ashock may be delivered to a subject, and also renders a cue on thedisplay 620 indicating that the likelihood of success is very good.Still other embodiments are possible.

The patient treatment module 616 may also be configured to provide aninput to each one of the speaker 618, display 620, and switch 606, topresent indications that show the status of chest and/or abdominalcompressions being provided mechanically or manually to the patient, orto prompt such actions when they are being performed manually. Forexample, the patient treatment module may be programmed to promptactuation of belts 626, 628 or to prompt human rescuers to provide chestand/or abdomen compressions in an phase-offset manner in the waysdiscussed above, such as by speaking timed commands to cause rescuers toprovide treatment to a patient in time and properly out-of-phase.

FIG. 7 is a schematic diagram of a computer system 700. The system 700can be used for the operations described in association with any of thecomputer-implement methods described previously, according to oneimplementation. The system 700 is intended to include various forms ofdigital computers, such as laptops, desktops, workstations, personaldigital assistants, servers, blade servers, mainframes, and otherappropriate computers. The system 700 can also include mobile devices,such as personal digital assistants, cellular telephones, smartphones,and other similar computing devices. Additionally the system can includeportable storage media, such as, Universal Serial Bus (USB) flashdrives. For example, the USB flash drives may store operating systemsand other applications. The USB flash drives can include input/outputcomponents, such as a wireless transmitter or USB connector that may beinserted into a USB port of another computing device.

The system 700 includes a processor 710, a memory 720, a storage device730, and an input/output device 740. Each of the components 710, 720,730, and 740 are interconnected using a system bus 750. The processor710 is capable of processing instructions for execution within thesystem 700. The processor may be designed using any of a number ofarchitectures. For example, the processor 710 may be a CISC (ComplexInstruction Set Computers) processor, a RISC (Reduced Instruction SetComputer) processor, or a MISC (Minimal Instruction Set Computer)processor.

In one implementation, the processor 710 is a single-threaded processor.In another implementation, the processor 710 is a multi-threadedprocessor. The processor 710 is capable of processing instructionsstored in the memory 720 or on the storage device 730 to displaygraphical information for a user interface on the input/output device740.

The memory 720 stores information within the system 700. In oneimplementation, the memory 720 is a computer-readable medium. In oneimplementation, the memory 720 is a volatile memory unit. In anotherimplementation, the memory 720 is a non-volatile memory unit.

The storage device 730 is capable of providing mass storage for thesystem 700. In one implementation, the storage device 730 is acomputer-readable medium. In various different implementations, thestorage device 730 may be a floppy disk device, a hard disk device, anoptical disk device, or a tape device.

The input/output device 740 provides input/output operations for thesystem 700. In one implementation, the input/output device 740 includesa keyboard and/or pointing device. In another implementation, theinput/output device 640 includes a display unit for displaying graphicaluser interfaces.

The features described can be implemented in digital electroniccircuitry, or in computer hardware, firmware, software, or incombinations of them. The apparatus can be implemented in a computerprogram product tangibly embodied in an information carrier, e.g., in amachine-readable storage device for execution by a programmableprocessor; and method steps can be performed by a programmable processorexecuting a program of instructions to perform functions of thedescribed implementations by operating on input data and generatingoutput. The described features can be implemented advantageously in oneor more computer programs that are executable on a programmable systemincluding at least one programmable processor coupled to receive dataand instructions from, and to transmit data and instructions to, a datastorage system, at least one input device, and at least one outputdevice. A computer program is a set of instructions that can be used,directly or indirectly, in a computer to perform a certain activity orbring about a certain result. A computer program can be written in anyform of programming language, including compiled or interpretedlanguages, and it can be deployed in any form, including as astand-alone program or as a module, component, subroutine, or other unitsuitable for use in a computing environment.

Suitable processors for the execution of a program of instructionsinclude, by way of example, both general and special purposemicroprocessors, and the sole processor or one of multiple processors ofany kind of computer. Generally, a processor will receive instructionsand data from a read-only memory or a random access memory or both. Theessential elements of a computer are a processor for executinginstructions and one or more memories for storing instructions and data.Generally, a computer will also include, or be operatively coupled tocommunicate with, one or more mass storage devices for storing datafiles; such devices include magnetic disks, such as internal hard disksand removable disks; magneto-optical disks; and optical disks. Storagedevices suitable for tangibly embodying computer program instructionsand data include all forms of non-volatile memory, including by way ofexample semiconductor memory devices, such as EPROM, EEPROM, and flashmemory devices; magnetic disks such as internal hard disks and removabledisks; magneto-optical disks; and CD-ROM and DVD-ROM disks. Theprocessor and the memory can be supplemented by, or incorporated in,ASICs (application-specific integrated circuits).

To provide for interaction with a user, the features can be implementedon a computer having a display device such as a CRT (cathode ray tube)or LCD (liquid crystal display) monitor for displaying information tothe user and a keyboard and a pointing device such as a mouse or atrackball by which the user can provide input to the computer.Additionally, such activities can be implemented via touchscreenflat-panel displays and other appropriate mechanisms.

The features can be implemented in a computer system that includes aback-end component, such as a data server, or that includes a middlewarecomponent, such as an application server or an Internet server, or thatincludes a front-end component, such as a client computer having agraphical user interface or an Internet browser, or any combination ofthem. The components of the system can be connected by any form ormedium of digital data communication such as a communication network.Examples of communication networks include a local area network (“LAN”),a wide area network (“WAN”), peer-to-peer networks (having ad-hoc orstatic members), grid computing infrastructures, and the Internet.

The computer system can include clients and servers. A client and serverare generally remote from each other and typically interact through anetwork, such as the described one. The relationship of client andserver arises by virtue of computer programs running on the respectivecomputers and having a client-server relationship to each other.

Many other implementations other than those described may be employed,and may be encompassed by the following claims.

What is claimed is:
 1. A method for providing emergency care to apatient of an adverse cardiac event, the method comprising: causingmultiple chest compressions to be provided to the patient; and causingmultiple inducements of ventilation to be provided to the patient,wherein particular ones of the multiple chest compressions overlaptime-wise with corresponding ones of the multiple inducements ofventilation, and are substantially out of phase with the correspondingones of the multiple inducements of ventilation.
 2. The method of claim1, wherein the chest compressions and the inducements of ventilation areperformed at substantially constant rates that substantially match eachother.
 3. The method of claim 2, wherein each of the particular ones ofthe chest compressions begin while the corresponding ones of theinducements of ventilation are occurring.
 4. The method of claim 3,wherein each of the particular ones of the chest compressions begin whenthe corresponding ones of the inducements of ventilation are aboutone-quarter complete.
 5. The method of claim 2, wherein each of theparticular ones of the chest compressions are performed approximately 90or 270 degrees out of phase with the corresponding ones of theinducements of ventilation.
 6. The method of claim 2, wherein downwardforce on the patient's chest is applied for each of the particular onesof the chest compressions while downward force is removed from thepatient's abdomen during the corresponding ones of the inducements ofventilation.
 7. The method of claim 1, wherein the multiple chestcompressions are provided by an automatic chest compression unit and themultiple inducements of ventilation are provided by an automaticmechanical ventilator.
 8. The method of claim 7, wherein the chestcompression unit comprises a belt wrapped around the patient's chest ora piston pressing against the patient's chest, and the automaticmechanical ventilator comprises a cuirass.
 9. The method of claim 7,further comprising automatically adaptively varying parameters of thechest compressions, the inducements of ventilation, or both, in responseto electronically monitoring a condition of the patient while the chestcompressions are provided to the patient.
 10. The method of claim 9,wherein automatically adaptively varying parameters of the chestcompressions comprising changing a manner in which the chestcompressions, inducements of ventilation, or both, are provided to thepatient, measuring a resulting change in one or more patient-dependentparameters, and selecting new parameters for provision of chestcompression, inducements of ventilation, or both based on the measuredresulting change.
 11. A system for providing coordinated chestcompressions and ventilation to a medical patient, the systemcomprising: a substrate arranged to press against a patient; a chestcompressor attached to the substrate and positioned to provide chestcompressions to the patient; and a mechanical ventilator attached to thesubstrate and positioned to engage the patient at the abdomen to induceventilations of the patient.
 12. The system of claim 11, furthercomprising an electronic controller programmed to actuate the chestcompressor and the mechanical ventilator so as to align chestcompressions of the patient and ventilation of the patient in apredetermined manner.
 13. The system of claim 11, wherein the electroniccontroller is programmed to cause the chest compressions and ventilationto be performed at substantially constant rates that substantially matcheach other.
 14. The system of claim 13, wherein each of particular onesof the chest compressions begin while corresponding ones of theventilations are already occurring.
 15. The system of claim 14, whereinthe controller is programmed so that each of the particular ones of thechest compressions begin when the corresponding ones of the ventilationsare about one-quarter complete.
 16. The system of claim 14, wherein eachof the particular ones of the chest compressions are performedapproximately 90 or 270 degrees out of phase with the corresponding onesof the ventilations.
 17. The system of claim 12, wherein downward forceon the patient's chest is applied for each of the particular ones of thechest compressions while downward force is removed from the patient'sabdomen during the corresponding ones of the ventilations.
 18. Thesystem of claim 11, wherein the mechanical ventilator comprises acuirass.
 19. The system of claim 11, wherein the chest compressorcomprises a belt positioned to wrap around the patient's chest and to beshortened in order to apply chest compressions to the patient.
 20. Thesystem of claim 19, wherein the mechanical ventilator comprises acuirass.
 21. The system of claim 20, wherein the cuirass ispneumatically powered.
 22. The system of claim 21, wherein the curiassreceives pneumatic power from a mechanism that is mechanically coupledto a motor that drives the belt.
 23. The system of claim 12, wherein thecontroller is programmed to automatically adaptively vary parameters ofthe chest compressions, the ventilations, or both, in response toelectronically monitoring a condition of the patient while the chestcompressions are provided to the patient.
 24. The method of claim 1,further comprising starting each of multiple chest compressions in aseries of chest compressions during a time at which correspondingcompressions or holds of compressions are being performed forcorresponding multiple abdominal compressions in a series of abdominalcompressions.